1. Field of the Invention
In one aspect this invention relates to storage cases for batteries. In a further aspect this invention relates to a battery casing for extending armored vehicle battery life.
2. Prior Art
In general ground vehicles have one or more storage batteries as a means to store electrical energy for starting the vehicle and operating auxiliary equipment when the vehicle""s prime mover is turned off. Armored combat type vehicles present unusual and extreme problems for storage batteries. Such vehicles must maintain hull or outer structure integrity in order to provide protection against various projectiles. Thus, the use of openings in the hull structure must be minimized both in number and size. Also the structure of combat vehicles results in a closed exterior that admits to little or no airflow by convection through the hull or engine compartment. In addition, military vehicles are exposed to weather extremes that severely stress the components while failure can create casualties.
In armored vehicles exposed to desert conditions the sun will heat the vehicle""s armor to temperatures in the 150 to 180 F. range which in turn will raise the battery temperature to a similar range even when not operating. When operating and the batteries are working or being charged, the battery""s temperatures will climb still higher. The result is water evaporates from the battery fluid and diminishes the battery capacity and efficiency. During the most severe high temperature ambient conditions it becomes necessary to add distilled water to the battery on a daily basis since the battery temperature will approach the boiling point of water with a resulting very high rate of evaporation. Because the batteries are under the armor shell they are difficult to service and the possibility of failure is raised. In addition to high ambient temperatures, combat vehicles are exposed to large quantities of air borne dust. Any battery ventilation system should account for the dusty conditions and have means for particle removal, preferably in a passive mode.
The location of the batteries creates yet a further problem. Because the batteries are located under the armor shell, the preference is to site them near the engine which in turn exposes them to the effects of heat generated by the prime mover. Experience has been that in tanks operating under desert environments, the average life of a battery will be about one year due to the constant evaporation and resulting use under less than optimal conditions. This short life span results in high replacement and maintenance costs. In addition, to increased cost, the decrease in readiness represents an increase in risk to the troops.
It would be desirable to have a battery supporting and protecting structure that will help maintain the batteries near the ambient temperature even when the surrounding portion of the vehicle gets overly heated in order to save battery life and increase readiness. It would be further desirable to insulate the battery supporting structure to minimize heat transfer from the surrounding area into the battery support during prime mover operation. Still further it would be desirable to have a structure that will have increased ventilation as a function of temperature in the battery storage area. Yet another desirable feature would be means to remove a substantial portion of any dust or other air born matter entering the ventilation system. Battery compartment ventilation minimizes dust accumulation, lowers battery temperature, and evacuates explosive hydrogen gas created during battery charging.
Briefly the present invention is directed to a battery storage system for holding and protecting the storage batteries used in an armored combat vehicle. The storage system includes a battery case having a top, bottom, sides and ends so as to form an enclosure that holds the batteries in a spaced configuration within the case. The sides and top of the case are insulated so as to minimize the thermal effects caused by heat from the surrounding engine components and armor materials. A supporting grid supports the batteries apart from the case bottom to permit the circulation of air under and around the batteries for cooling purposes. The case has a thermally controlled valve member located near a first end of the case on the case""s top surface. A conduit connects a second end of the battery case distal the valve member to an inlet on the vehicle""s surface that allows the entry of ambient air. A solids entrapping means is located between the battery box and the inlet, the solid entrapping means being adapted to passively separate solids from the flowing air prior to entry of the cooling air into the case.
In a battery storage box according to this invention when the battery case temperature exceeds a predetermined value the valve opens allowing ambient air to flow through the conduit and around the batteries reducing their temperature. The cooling air first passes through the solids entraining means to minimize the solids that enter the battery enclosure.